![]() ![]() Metamaterials were first hypothesized in 1968 by Russian theorist Victor Veselago, who theorized that a wave could interact with metamaterials in a way fundamentally different from natural materials, which all have positive permeability and permittivity.Īll natural materials bend electromagnetic radiation in the same predictable direction: away from a line perpendicular to their surface (away from “normal”). By arranging the metamaterial so that their index of refraction diverts waves upward, around and then down again, the shielded wavelengths are diverted around the object so that it is invisible to observers. The anti-cloaking layer was simulated using anisotropic optical materials with a negative index of refraction.Īn invisibility cloak works by surrounding an object with anisotropic metamaterials with a variable index of refraction by virtue of their permittivity and permeability being less than that of free space. It was, however, simulated for a perfect electrical conductor at a wavelength of 150 millimeters (2 GHz). The Chinese proposal is theoretical and has yet to be implemented in a working device. ![]() No one has yet proposed an approach that would cloak all wavelengths. In addition, researchers working at the Energy Department's Ames Laboratory have demonstrated the world’s first cloak for visible wavelengths.Īll the cloaking devices, however, only shield objects from observation using specific bands of electromagnetic radiation. researchers have demonstrated a working cloak that shields a five-inch-square area from microwave wavelengths.Ī separate group at Duke, led by professor Steven Cummer, subsequently demonstrated a working acoustic cloak that could render submarines invisible to sonar. Schurig developed the invisibility cloak in 2006 as a post-doctoral fellow at Duke University. ![]()
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